The invention relates to a rotor nozzle for a high-pressure cleaning appliance with a housing, which comprises at least one inlet for a liquid opening tangentially into the housing, and which is provided in a front wall with a pan-shaped depression with a central opening, and with a nozzle body arranged in the housing, the nozzle body having a through-channel and being supported with a spherical end in the pan-shaped depression, and the longitudinal axis of the nozzle body being inclined to the longitudinal axis of the housing, it being possible for liquid in the housing to be caused to rotate about the longitudinal axis of the housing by the liquid flowing via the at least one inlet into the housing, and the nozzle body rotating together with the rotating liquid and in doing so bearing with a contact surface at its circumference against the inside wall of the housing.
Such rotor nozzles are known, for example, from DE 41 29 026 C1. With these a compact jet of liquid circulating on the surface of a cone can be generated, which, for example, for cleaning purposes can be directed onto a surface to be cleaned. For this purpose, the inlet of the housing can be connected to a high-pressure cleaning appliance, so that liquid under high pressure can be supplied to the housing. In the housing there is located a nozzle body, which is only mounted at one side on the pan-shaped depression and otherwise can move in the housing about the longitudinal axis of the housing. The nozzle body has a through-channel through which the liquid can pass through the depression of the housing, which has an opening. The longitudinal axis of the nozzle body is inclined in relation to the longitudinal axis of the housing. Owing to the liquid entering the housing tangentially, the nozzle body is pressed into the pan-shaped depression, which forms a bearing for the nozzle body, and, at the same time, the nozzle body is caused to rotate about the longitudinal axis of the housing. As a consequence of this, the exiting jet of liquid also describes the desired circular movement, so that a relatively large surface can be acted upon with liquid at a pressure comparable to spot jet nozzles.
The supplying of the liquid under pressure via the inlet opening tangentially into the housing ensures that liquid located in the housing is rotated about the longitudinal axis of the housing and the nozzle body is thereby also rotated about the longitudinal axis of the housing by a rotating liquid column forming inside the housing. The at least one tangential inlet does, however, form a flow resistance for the liquid, which results in flow losses. In order to reduce the flow resistance, the diameter of the at least one tangential inlet could be increased. However, this then has the consequence that the flow velocity of the liquid in the area of the at least one tangential inlet is reduced, and this, in turn, may have the consequence that the nozzle body cannot in all cases, be reliably caused to rotate about the longitudinal axis of the housing. In particular, the so-called “start-up behavior” of the nozzle body may be impaired. Start-up behavior is to be understood as initiation of the rotation of the nozzle body. Before liquid under pressure is supplied to the housing, the nozzle body is at rest relative to the inside wall of the housing, i.e., it is not yet executing a rotational movement about the longitudinal axis of the housing. When liquid under pressure is now supplied via the at least one tangential inlet, the static friction between the nozzle body and the inside wall of the housing must first be overcome in order to be able to cause the nozzle body to rotate. A relatively large initial frictional force must, therefore, first be overcome in order to move the nozzle body. When the nozzle body then executes a rotational movement, it is the sliding friction, which is usually smaller than the initial static friction, that is then responsible for the frictional behavior of the nozzle body at the inside wall of the housing. As a consequence of this, a lower force is required for maintaining a rotational movement of the nozzle body about the longitudinal axis of the housing than for initiating the movement.
If the flow cross section of the at least one tangential inlet is now increased, in order to reduce flow losses in the area of the inlet, the flow velocity of the liquid in the area of the inlet is thereby reduced, and this may, in turn, have the consequence that the force exerted by the liquid on the nozzle body is not sufficient to cause the nozzle body to rotate about the longitudinal axis of the housing.
The object of the present invention is to so develop a rotor nozzle of the kind mentioned at the outset that flow losses can be reduced in the area of the rotor nozzle without operation of the rotor nozzle, in particular, start-up behavior of the nozzle body, thereby being noticeably impaired.